Battery packs have been already used in various portable devices such as mobile phones, digital still cameras, portable game machines, laptop personal computers, and electric tools. And now, besides them, battery packs are being used in the fields requiring a higher output and a higher capacity, such as electric power-assisted bicycles, electric cars, and, further, household electric storage apparatuses.
One of secondary battery cells that are most dominantly used now as a secondary battery cell incorporated in a battery pack is a lithium-ion secondary battery cell. The lithium-ion secondary battery cell is very widely used due to a number of features such as being repeatedly usable by charging, having a high voltage output, having a high energy density, having a small amount of self-discharge, and having a long lifetime. Further, in order to meet a demand for a device with a higher output and a higher capacity, there are increasing cases where many secondary battery cells (unit cells) are connected in series or parallel to be used in the mode of an assembled battery. Such a method for use has a great advantage. However, an amount of energy to be treated becomes very huge, and therefore it is necessary to be further more careful in the handling than in the past.
In order to determine whether or not a battery pack mounted to a power consumption device is one that can be used safely for the power consumption device, many battery authentication systems for authenticating a secondary battery cell provided to a battery pack have been introduced. The technology of reading out individual identification information such as an ID number from a secondary battery cell including a wireless IC tag (integrated circuit) is well-known from Japanese Patent Application Laid-open No. 2006-236806, for example.